German Patent Publication No. DE 199 12 301 describes a safety device for a motor vehicle, in particular a passenger vehicle, having at least one impact sensor and one control unit that triggers operation of the vehicle brakes in accordance with the sensor signal, including a signal analyzer circuit which is designed according to the present invention so that the extent of the damage in the event of a rear-end collision is minimized and collision-related damages are largely prevented by the fact that the analyzer circuit responds when the sensor signal rises above a predetermined upper limit value and subsequently drops below a predetermined lower limit value such that the operating brakes of the vehicle are activated simultaneously with the end of the impact shock.